The present disclosure relates to an image forming apparatus including an attachable/detachable image forming unit.
In an image forming apparatus such as a printer or a multifunction peripheral, there is a construction that an image forming unit such as a photosensitive drum or a development device is attachably/detachably provided at an apparatus main body, and a driving source which drives the image forming unit is provided at the apparatus main body. Such a construction requires a mechanism which transmits a rotation force of the driving source to the image forming unit attached to the apparatus main body.
As a mechanism which transmits the rotation force of the driving source to the image forming unit, there is employed a gear transmission manner of engaging a gear provided at the image forming unit and a gear provided at a driving shaft of the driving source or a coaxial driving transmission manner which coaxially couples the driving shaft of the image forming unit and the driving shaft of the driving source with each other by employing a joint member. In recent years, the coaxial driving transmission manner has become mainstream owing to advantages that space saving can be achieved on the image forming unit side, heating can be restricted, and gear phase alignment can be achieved on the apparatus main body side in the photosensitive drum or the like.
Incidentally, at the time of carrying out replacement or maintenance of the image forming unit, a serviceman or a user attaches or detaches the image forming unit, and however, if the image forming unit is not attached at a normal position under a predetermined operating environment, a malfunction or a damage of the image forming apparatus can occur. In particular, in the coaxial driving transmission manner, in a case where the image forming unit is attached or detached in a direction orthogonal to the driving shaft of the driving source, if the image forming unit is incorrectly attached, the driving shaft of the image forming unit and the driving shaft of the driving source interfere with each other, and a coupling part of the driving shafts may be damaged.
In order to prevent incorrect attachment of the image forming unit, there is an image forming apparatus configured so that if the image forming unit is incorrectly attached, the attached posture is apparently clearly different from a normal attached posture. Also, there is an image forming apparatus in which, in a case where the image forming unit is incorrectly attached, a handle for unmovably fixing the image forming unit to the image forming apparatus is made inactive.
However, these image forming apparatuses both cause a user to recognize incorrect attachment after the image forming unit has been incorrectly attached, and it is not an essential measure for solving a problem such as damage occurred at the time of incorrect attachment.